The present invention relates to a multilayer circuit board electrified with a high current and a method for manufacturing the multilayer circuit board.
Multilayer circuit boards have been lately in great demand for densely packaging semiconductor devices and electric components such as a condenser and a resistor. Such a multilayer circuit board can be manufactured, for example, by: stacking conductive pattern films, in each of which conductive patterns made of, for example, copper have been patterned out on a thermoplastic resin film, which is an insulating layer; and integrating the stacked body by heat pressing.
With respect to the above multilayer circuit board, there have been demands, for example, for mounting a power device on the board in order to form a power source circuit or for building a specialty component such as a coil on or in the board in order to diversify the application. In such an instance, it is necessary to electrify the conductive patterns electrically connected to the power device and the coil with a high current, so the conductive patterns need to become relatively thick in order to increase the current-carrying capacity thereof in the above multilayer circuit board.
However, if the current-carrying capacity was increased by thickening the conductive patterns, it would become difficult to miniaturizing the conductive patterns because the etching precision when the conductive patterns are patterned out by etching would worsen. Moreover, if extremely thick conductive patterns were used, the thermoplastic resin films, on which the thick conductive patterns have been formed, could not conformably cover the thick conductive patterns when the thermoplastic resin films are molten by heat pressed. As a result, voids would be generated, or the thermoplastic resin films would be delaminated.